Enzyme-based biosensors are devices in which an analyte-concentration-dependent biochemical reaction signal is converted into a measurable physical signal, such as an optical or electrical signal. Such biosensors are widely used in the detection of analytes in clinical, environmental, agricultural and biotechnological applications. Analytes that can be measured in clinical assays of fluids of the human body include, for example, glucose, lactate, cholesterol, bilirubin and amino acids. The detection of analytes in biological fluids, such as blood, is important in the diagnosis and the monitoring of many diseases.
Biosensors that detect analytes via electrical signals, such as current (amperometric biosensors) or charge (coulometric biosensors), are of special interest because electron transfer is involved in the biochemical reactions of many important bioanalytes. Systems include those intended for in vitro use (e.g., test strips) and those intended for in vivo use (e.g., in which at least a portion of a sensor is positioned in a user).
Typically, systems employ at least one working electrode and a sensing layer that includes an analyte-responsive enzyme in proximity thereto. Analyte monitoring systems may vary depending on a variety of factors such as the particular technology (e.g., amperometric, coulometry, optical, etc.) and the sensing material. For example, the sensing layer will vary depending on the analyte(s) of interest such as glucose oxidase or glucose dehydrogenase when the analyte of interest is glucose, and may employ a mediator and/or other components.
As analyte monitoring devices and methods, particularly glucose monitoring, becomes increasingly important for disease control, there is a continued interest for development of new analyte monitoring systems, including new sensing layers, that are highly stable, and that are versatile in that they may be employed with a variety of different enzymes. Such sensing layers that simplify manufacturing processes are also desirable.